The present invention mainly relates to an absorbent article, such as a sanitary napkin, a pantiliner, a vaginal discharge sheet, an incontinence pad, or a toiletry, and, specifically, relates to structures of three-dimensional gathers formed on both side ends on the top surface side of the absorbent article.
As absorbent articles such as sanitary napkins, pantiliners, and incontinence pads, conventionally known are those each having a liquid-impermeable back sheet of a polyethylene sheet, a polyethylene laminated nonwoven fabric, or the like; a liquid-permeable top sheet of a nonwoven fabric, a liquid-permeable plastic sheet, or the like; and an absorber composed of cotton-like pulp or the like interposed therebetween.
In such types of absorbent articles, in order to prevent excreted body fluid from leaking from the groin portion, three-dimensional gathers standing on the top surface side in various shapes along the longitudinal direction of the absorbent articles are formed. Examples of the sanitary napkin having a pair of three-dimensional gathers on either side on the top surface side are disclosed in, for example, JP-A-2001-145667; JP-A-2001-95842; JP-A-2002-656; and JP-A-64-68503.
However, the three-dimensional gathers shown in the above documents are formed on either side so as to correspond to the body fluid excretion portions, and they have a problem that they cannot properly prevent side leakage of body fluid, for example, excreted when a person lies on her back in bed, that temporarily flows to the buttock side and then diffuses laterally.
Accordingly, the following JP-A-2006-280580 and JP-A-2006-280583 disclose absorbent articles additionally provided with three-dimensional gathers on the buttock side. Specifically, the absorbent article according to JP-A-2006-280580 has front portion side three-dimensional gathers that stand on the top surface side by means of the contractive force of an elastic stretchable member on either side on the top surface side so as to correspond to the body fluid excretion portion of the absorbent article and also has back portion side three-dimensional gathers that stand on the top surface side by means of the contractive force of an elastic stretchable member on either side on the top surface side at the back portion of the absorbent article, so that non-standing portions are present between the front portion side three-dimensional gathers and the back portion side three-dimensional gathers. The absorbent article according to JP-A-2006-280583 has two sets of three-dimensional gather components each disposed over the longitudinal direction on either side on the top surface side of the absorbent article. The three-dimensional gather components of one of the two sets are configured so as to stand on the top surface side by means of the contractive force of an elastic stretchable members at portions corresponding to the body fluid excretion portion, and the three-dimensional gather components of the other of the two sets are configured so as to stand on the top surface side by means of the contractive force of an elastic stretchable member at portions corresponding to the buttock side.
However, in the three-dimensional gathers according to JP-A-2006-280580, though body shapes at the body liquid excretion portion and the buttock side portion are absolutely different from each other, the three-dimensional gathers disposed at the body liquid excretion portion and the buttock side portion have the same shapes. In particular, the effect of the three-dimensional gathers for preventing the flow at the buttock side portion is not sufficiently obtained. In the three-dimensional gathers according to JP-A-2006-280583, the three-dimensional gathers are formed so as to stand to form a dogleg-shaped cross section at the body fluid excretion portion and so as to stand in a linear fashion toward the outside at the buttock side portion. In particular, though it is possible to make the three-dimensional gathers fit to the curves of the buttocks at the buttock side, since two sets of three-dimensional gather components are provided so that one set forms three-dimensional gathers at the body fluid excretion portion and the other set forms three-dimensional gathers at the buttock side, for example, there is a problem in that the amount of the member forming the three-dimensional gathers is twice compared to usual one.
On the other hand, as shown in JP-A-2002-656, in the three-dimensional gather having a T-shaped cross section having a base wall portion standing from the surface of an absorbent article and inward and outward protrudes protruding toward the inside and the outside, respectively, of the absorbent article from the upper portion of the base wall portion, as shown in FIG. 11, since the outward protrude 51 that comes into contact with the crotch portion of a wearer is formed by laterally protruding from the base wall portion 52 being the standing portion of the three-dimensional gather, when the absorbent article is worn, the groin portion presses the outward protrude 51 to make the whole three-dimensional gather 50 fall down on the surface of the absorber as shown in (B) of FIG. 11. Similarly, this problem is likely caused in the three-dimensional gather having a Σ-shaped cross section described in JP-A-2001-145667 by that the skin patch portion is pressed and in the three-dimensional gather having a dogleg-shaped cross section described in JP-A-2001-95842 by that the folding point of the dogleg shape is pressed.
In the state in that the three-dimensional gather falls down on the absorber surface, the absorbent area is reduced to prevent the excreted body fluid from being absorbed by the absorber, which has a problem to cause side leakage of the body fluid moving along the three-dimensional gather, although the absorber still has an absorbing ability. Furthermore, as shown in FIG. 11(B), if the protrude portion falls down on the absorber surface, the distance from the crotch becomes ununiform to deteriorate fitting feeling and to cause leakage of body fluid.